'We think the photograph on the postcard was taken by Beatrix herself, though it could have been taken by her father, who was a prolific photographer.

'We know quite a lot about Benjamin because Beatrix wrote about him in her Journal, and he was the model for most of the rabbits in her early published work in the 1890s - greetings cards and so on - that predated the little books.'

In The Tale of Benjamin Bunny, the title character joins his cousin Peter Rabbit to return to Mr McGregor's garden and look for the clothes Peter left there in the first book.

During the risky escapade, the two bunnies become trapped under a basket by Mr McGregor's cat and have to be rescued by Benjamin's father.